TM 55-4920-413-13&P
i. Rotor Speed.
(4) Measure frequency. Frequency counter will indicate
between 11,190 and 11,302 Hz. If not, perform Troubleshoot-
NOTE
ing Table 4-12.
Observe amplitude limitations of frequency count-
(5) Set ROTOR SPEED HI/LO switch to LO. Frequen-
er, unattenuated inputs can cause damage.
cy counter will indicate O. (Disregard residual noise count.) If
(1) Connect frequency counter to connector NO 1 pins A
not, perform Troubleshooting Table 4-12.
(HI) and B (LOW), using two leads and adapter.
(6) Set ROTOR SPEED CAL/NOR to NOR and adiust
ROTOR SPEED variable control from fully CCW to full.
(2) Set ROTOR SPEED CAL/NOR switch to CAL and
Frequency counter indication will vary from O to 17,200 Hz
HI/LO switch to HI.
minimum. If not, perform Troubleshooting Table 4-12.
(3) Set ON-OFF-SIM ONLY switch to SIM ONLY.
(7) Set ON-OFF-SIM ONLY switch to OFF.
Table 4-12. Troubleshooting Rotor Speed (Hz) (AVIM).
NOTE
Before performing troubleshooting, remove frequency simulator A3 board and reconnect using extender board.
Trouble
Probable Cause
Remedy
HI-CAL – No
U4 pin 13 (337 Hz ±5 Hz)
First check loops 44 ( -) and 5 (+) for
Frequency Output
US pin, 4, -5 (675 Hz ±5 Hz)
11)246 Hz ±56 Hz and check U12 pin
7 (HI), U8 pins 4 HI, 5 HI, U12 pin 7
HI. Replace defective components,
Figures 4-8, 4-9, FO-3, FO-5, or
replace A3 board.
LO-CAL indicates Frequency (Hz)
HI/LOW Switch (S9)
Replace defective components,
greater than 0 HZ
Figures 4-8, 4-9, FO-3, FO-5, or
replace A3 board.
NOR-FULLY CCW
NOR Control (R4)
Replace defective components,
Frequency indication greater
(R5) (R8) or Q1
Figures 4-8, 4-9, FO-3, FO-5, or
than 0 HZ
replace A3 board.
NOR-FULLY CW
NOR Control (R4) Ql, Q6, Q11, or
Replace defective components,
NO Frequency Output
U1A (U1A, C6 or R6 amplitude)
Figures 4-8, 4-9, FO-3, FO-5, or
replace A3 board.
NOR-Frequency
Trim Resistor R1
Use decade resistor box and check
indication out of tolerance
or replace defective components,
Figures 4-8, 4-9, FO-3, FO-5, or
replace A3 board.
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